Disc brake conversion

I can supply a custom made 5 x 4" bolt pattern 8.75" axle package.
I am looking for a small pattern solution rear wheel solution that will allow me to keep my 14" Rallys. There does not seem to be a solution out there that does both, so I think the easiest solution is to drill a 5/4.5 for 5/4.

What I have : 64 Dart 8 3/4 with green bearings. stock Disks in the front dual master and I think a stock distribution valve. Also thinking about refurbing a power system from a 65 dart, but keeping the dual master.

So what do I need, and what can you do ?